/* ===============================================================================  
 * Copyright (c) 2010 Acid Frameworks
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 * 
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 * 
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 * THE SOFTWARE.
 * 
 * =============================================================================== */

using System;
using System.Collections.Generic;

namespace Acid.Rendering
{
    /// <summary>
    /// Timing utility used for measuring Frames Per Second.
    /// </summary>
    public class FramesPerSecond
    {
        private  Queue<DateTime>  timings;
        private  int              Samples   { get; set; }
        public   double           Value     { get; set; }

        /// <summary>
        /// Constructor
        /// </summary>
        public FramesPerSecond() : this(600) { }
       
        /// <summary>
        /// Contructor
        /// </summary>
        /// <param name="samples">The amount of sampling used in computing an average. Maximum is 60</param>
        public FramesPerSecond(int samples)
        {
            if (samples > 60) 
                samples = 60;

            this.Samples = samples;

            this.timings = new Queue<DateTime>(61);
        }
       
        /// <summary>
        /// Updates time interval. Computes averaged frames per seconds given the number of samples.
        /// </summary>
        public void Update()
        {
            DateTime now = DateTime.Now;

            timings.Enqueue(now);

            while (timings.Count > this.Samples)
            {
                DateTime then = timings.Dequeue();

                TimeSpan span = now - then;

                this.Value = (double)(this.Samples / span.TotalSeconds);
            }
        }
    }
}
